Environmentally friendly chemical-resistant high-pressure hydrogen transmission and storage coating and preparation method therefor

Abstract

The present invention relates to the technical field of hydrogen permeation resistance, and relates to an environmentally friendly chemical-resistant high-pressure hydrogen transmission and storage coating and a preparation method therefor. Montmorillonite is modified with dodecylbis(2-hydroxyethyl)methylammonium chloride, and zirconium oxide is deposited on the surface thereof to form a composite filler. The composite filler significantly improves the compatibility and dispersibility with a polymer matrix, and oxygen vacancies in zirconium dioxide are utilized to effectively adsorb and anchor hydrogen molecules, thereby further hindering diffusion and permeation of hydrogen. Cellulose nanocrystals are modified with stearic acid to successfully introduce hydrophobic groups, significantly reducing agglomeration phenomenon of the cellulose nanocrystals and improving the dispersibility and compatibility of the cellulose nanocrystals in a waterborne polyurethane emulsion. The modified cellulose nanocrystals provide the coating with excellent hydrogen barrier performance, chemical resistance, and mechanical strength, form a highly compact structure, effectively prevent hydrogen leakage, reduce pores and defects in the coating, and improve the compactness and hydrogen barrier performance of the coating.

Description

An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating and its preparation method Technical Field

[0001] This invention belongs to the field of hydrogen permeation barrier technology, and relates to an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating and its preparation method. Background Technology

[0002] Hydrogen, as one of the most abundant elements in nature, is increasingly attracting global attention for its unique energy value. Hydrogen can be efficiently produced through processes such as water electrolysis using renewable energy sources, and its combustion produces extremely high energy density. Furthermore, this process does not generate greenhouse gases or other harmful substances, demonstrating its enormous potential as a future clean energy carrier. However, despite the promising prospects of hydrogen energy applications, its transportation and storage in practical applications face significant technological challenges.

[0003] Due to their extremely small diameter, hydrogen atoms possess significantly higher permeability and diffusivity compared to metal atoms. This means that during hydrogen transport and storage, hydrogen atoms can easily penetrate the walls of metallic hydrogen pipelines and storage containers, causing hydrogen embrittlement. Hydrogen embrittlement not only significantly alters the mechanical properties of metallic materials, reducing their strength and toughness, but can also lead to sudden material fracture in extreme cases, posing a serious threat to the safety and reliability of hydrogen energy systems. Furthermore, once hydrogen embrittlement occurs within a material, it is an irreversible process, and its effects cannot be eliminated through subsequent repair methods. To mitigate the permeation and diffusion of hydrogen in metals, preparing hydrogen-barrier coatings on the material surface has become an effective method to delay or prevent hydrogen from penetrating into the material's interior and thus prevent hydrogen embrittlement. Therefore, developing a novel hydrogen-barrier coating that is both environmentally friendly and possesses excellent chemical resistance is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating and its preparation method, which has excellent hydrogen barrier properties and chemical resistance.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating is provided. The coating formulation is as follows (by weight): 60-80 parts waterborne polyurethane emulsion, 30-40 parts modified cellulose nanocrystals, 5-15 parts composite filler, 5-7 parts dispersant, 2-3 parts crosslinking agent, and 1-2 parts film-forming aid.

[0007] The preparation method of the composite filler is as follows:

[0008] S1-1: Add 10-20 parts by weight of nano-sized sodium-based montmorillonite to 280-300 parts by weight of deionized water and stir at 40°C for 1.5 h to obtain suspension A;

[0009] S1-2: Add 5-10 parts by weight of methyldodecylbis(hydroxyethyl)ammonium chloride to 90-100 parts by weight of deionized water, sonicate for 30 minutes, then add 1-2 parts by weight of hydrochloric acid solution, and continue sonicating for 30 minutes to obtain solution B.

[0010] S1-3: Add solution B dropwise to suspension A, stir at 80℃ for 1.5h, filter and wash with 70% ethanol solution, dry at 100℃ for 12h to obtain powder C;

[0011] S1-4: Mix 10-20 parts by weight of zirconium isopropoxide and 70-90 parts by weight of 50% ethanol solution, add powder C, reflux at 60°C for 1 hour, wash with deionized water and anhydrous ethanol, calcine in a muffle furnace for 1 hour at 400-600°C, and then ball mill in a ball mill for 1.5 hours at a speed of 400-500 r / min to obtain the composite filler.

[0012] Furthermore, the preparation method of modified cellulose nanocrystals is as follows:

[0013] S2-1: Add 20-40 parts by weight of cellulose nanocrystals to 60-80 parts by weight of deionized water and disperse at a stirring speed of 800-1000 r / min for 30 min to obtain suspension D;

[0014] S2-2: Add 3-5 parts by weight of stearic acid to 20-30 parts by weight of anhydrous ethanol, stir at 80-90℃ for 1 hour to obtain solution E;

[0015] S2-3: Mix suspension D and solution E, stir at 70~80℃ for 1.5h, wash with deionized water and anhydrous ethanol, and freeze dry in a freeze dryer to obtain the modified cellulose nanocrystals.

[0016] Furthermore, the dispersant is one of polyethylene glycol and polypropylene glycol.

[0017] Furthermore, the crosslinking agent is one or more of the silane coupling agents KH550, KH560 and KH570.

[0018] Furthermore, the concentration of the hydrochloric acid solution in S1-2 is 6M.

[0019] Furthermore, according to claim 1, the environmentally friendly chemical-resistant high-pressure hydrogen transport and storage coating is characterized in that the dropping rate of solution B in S1-3 is 1 mL / min.

[0020] Furthermore, the freeze-drying temperature of the freeze dryer in S2-3 is -30℃, and the freeze-drying time is 12h.

[0021] Furthermore, the film-forming aid is alcohol ester 12.

[0022] A method for preparing an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, the specific steps of which are as follows:

[0023] S9-1: Mix the waterborne polyurethane emulsion, modified cellulose nanocrystals, composite filler, dispersant, crosslinking agent and film-forming aid according to the formula for 30 minutes to obtain the coating;

[0024] S9-2: The steel pipe is added to a 75% ethanol solution and sonicated for 20 minutes. It is then dried in a vacuum drying oven at 60°C for 12 hours. The surface of the steel pipe is then subjected to high-energy shot peening to make its surface nano-sized, thus obtaining the pretreated steel pipe.

[0025] S9-3: Spin-coating the coating onto the inside of the pretreated steel pipe and drying it to obtain the coating.

[0026] An application of an environmentally friendly, chemical-resistant, high-pressure hydrogen transport and storage coating, which can be applied to hydrogen transport pipelines and hydrogen storage cylinders.

[0027] Polymer hydrogen barrier properties are based on the "like dissolves like" principle. Hydrogen is a nonpolar molecule and therefore tends to dissolve in nonpolar solutions. When polymer materials have a very dense structure, they strictly limit hydrogen diffusion. Cellulose nanocrystals, as a nanoscale material derived from biomass, possess characteristics such as high strength, high aspect ratio, biodegradability, and good hydrogen barrier properties. However, the large specific surface area and abundant hydrophilic hydroxyl groups on the surface of cellulose nanocrystals, coupled with strong intermolecular hydrogen bonding, make them prone to aggregation in organic polymer matrices, resulting in poor dispersibility and compatibility. Cellulose nanocrystals are also sensitive to water and lose their barrier properties when humidity increases. Stearic acid, as a long-chain fatty acid with both lipophilic long carbon chains and hydrophilic carboxyl groups, can undergo esterification with the hydroxyl groups on the surface of cellulose nanocrystals, thereby successfully introducing hydrophobic groups onto the surface of cellulose nanocrystals. This modification not only reduces the surface energy of cellulose nanocrystals but also significantly alters their surface wetting properties, thereby enhancing the interaction between cellulose nanocrystals and aqueous polyurethane emulsions. After modification with stearic acid, the number of hydroxyl groups on the surface of cellulose nanocrystals is significantly reduced, effectively weakening agglomeration and thus significantly improving their dispersibility in aqueous polyurethane emulsions. This effectively promotes thorough mixing of cellulose nanocrystals and aqueous polyurethane emulsions, enhancing their compatibility. Furthermore, the modified cellulose nanocrystals provide the coating with excellent chemical resistance and mechanical strength, enabling the coating to form a highly compact structure, effectively preventing hydrogen leakage, and helping to reduce porosity and defects in the coating, thereby further improving the film's density and hydrogen barrier properties.

[0028] Methyldodecylbis(hydroxyethyl)ammonium chloride, as a cationic surfactant, can exchange cations with the interlayer of sodium-based montmorillonite, thereby increasing the interlayer spacing and surface properties of montmorillonite. This helps improve the compatibility of montmorillonite with the polymer matrix, promotes dispersion, and further enhances the hydrogen barrier properties of the coating. Furthermore, the deposition of zirconium dioxide on montmorillonite to form a composite filler, with oxygen vacancies, acts as defect sites that can adsorb and anchor hydrogen molecules, further hindering hydrogen diffusion and penetration. This composite filler not only promotes a denser and more stable coating structure, effectively blocking hydrogen penetration, but also provides additional mechanical support, enhancing the overall strength of the coating. Simultaneously, the composite filler maintains good chemical stability, ensuring stable performance under various harsh environments. Moreover, the composite filler effectively combines with modified cellulose nanocrystals, forming excellent interfacial interactions, further improving the coating's density and reducing gas and liquid permeation channels. Both montmorillonite and zirconium dioxide in the composite filler are environmentally friendly materials that will not harm the environment, aligning with the concept of sustainable development.

[0029] High-energy shot peening of the steel pipe surface makes the surface nano-sized, allowing the coating to penetrate more effectively into the tiny gaps and pores on the steel pipe surface. This facilitates the coating's penetration into the steel pipe surface to form a mechanical interlocking structure, greatly improving the adhesion between the coating and the steel pipe.

[0030] The beneficial effects of this invention are:

[0031] (1) Montmorillonite was modified with methyl dodecyl dihydroxyethyl ammonium chloride and zirconium oxide was deposited on the surface to form a composite filler, which significantly improved the compatibility and dispersibility of the composite filler with the polymer matrix. The oxygen vacancies in zirconium dioxide were used as defect sites to effectively adsorb and anchor hydrogen molecules, further hindering the diffusion and penetration of hydrogen. It also provided additional mechanical support and chemical resistance, and enhanced the overall strength of the coating.

[0032] (2) By modifying cellulose nanocrystals with stearic acid, hydrophobic groups were successfully introduced, effectively weakening the aggregation of cellulose nanocrystals and significantly improving their dispersibility and compatibility in aqueous polyurethane emulsions, thereby enhancing the overall performance of the coating material. The modified cellulose nanocrystals provide the coating with excellent hydrogen barrier properties, chemical resistance, and mechanical strength, forming a highly compact structure that effectively prevents hydrogen leakage and reduces porosity and defects in the coating, further improving the coating's density and hydrogen barrier properties. Detailed Implementation

[0033] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0034] In the embodiments and comparative examples of this invention:

[0035] Waterborne polyurethane emulsion: purchased from Shanghai Yihe Biotechnology Co., Ltd.;

[0036] Cellulose nanocrystals: purchased from Shenzhen Huano Biotechnology Co., Ltd.;

[0037] Stearic acid: purchased from Hunan Ruhong Pharmaceutical Co., Ltd.;

[0038] Anhydrous ethanol: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0039] Sodium-based montmorillonite: purchased from Lingyuan Beibiansen Biotechnology Co., Ltd.;

[0040] Methyldodecylbishydroxyethylammonium chloride: purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.;

[0041] Zirconium isopropoxide: purchased from Shanghai Myriel Biochemical Technology Co., Ltd.;

[0042] Polyethylene glycol: purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.;

[0043] Polypropylene glycol: purchased from Shanghai Baoyang Baoxin Biotechnology Co., Ltd.;

[0044] Silane coupling agents KH550, KH560, and KH570 were purchased from Nanjing Quanxi New Materials Co., Ltd.

[0045] Alcohol ester 12: Purchased from Shanghai Biyang Industrial Co., Ltd. Example 1

[0046] An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, wherein the formulation 1 of the high-pressure hydrogen transport and storage coating is as follows (by weight): 70 parts waterborne polyurethane emulsion, 35 parts modified cellulose nanocrystals, 10 parts composite filler, 6 parts polyethylene glycol, 2.5 parts silane coupling agent KH550, and 121.5 parts alcohol ester.

[0047] The preparation method of the composite filler is as follows:

[0048] S1-1: Add 15 parts by weight of nano-sized sodium-based montmorillonite to 290 parts by weight of deionized water and stir at 40°C for 1.5 h to obtain suspension A;

[0049] S1-2: Add 8 parts by weight of methyldodecylbis(hydroxyethyl)ammonium chloride to 95 parts by weight of deionized water, sonicate for 30 min, then add 1.5 parts by weight of 6M hydrochloric acid solution, and continue sonicating for 30 min to obtain solution B;

[0050] S1-3: Add solution B dropwise to suspension A at a rate of 1 mL / min, stir at 80 °C for 1.5 h, filter and wash with 70% ethanol solution, dry at 100 °C for 12 h to obtain powder C;

[0051] S1-4: Mix 15 parts by weight of zirconium isopropoxide and 80 parts by weight of 50% ethanol solution, add powder C, reflux at 60°C for 1 hour, wash with deionized water and anhydrous ethanol, calcine in a muffle furnace for 1 hour at 500°C, and then ball mill in a ball mill for 1.5 hours at a speed of 450 r / min to obtain the composite filler.

[0052] The preparation method of modified cellulose nanocrystals is as follows:

[0053] S2-1: Add 30 parts by weight of cellulose nanocrystals to 70 parts by weight of deionized water and disperse at a stirring speed of 900 r / min for 30 min to obtain suspension D;

[0054] S2-2: Add 4 parts by weight of stearic acid to 25 parts by weight of anhydrous ethanol and stir at 85°C for 1 hour to obtain solution E;

[0055] S2-3: Mix suspension D and solution E, stir at 75°C for 1.5 h, wash with deionized water and anhydrous ethanol, freeze dry in a -30°C freeze dryer for 12 h to obtain the modified cellulose nanocrystals.

[0056] A method for preparing an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, the specific steps of which are as follows:

[0057] S9-1: Mix waterborne polyurethane emulsion, modified cellulose nanocrystals, composite filler, polyethylene glycol, silane coupling agent KH550 and alcohol ester 12 for 30 min according to formula 1 to obtain coating.

[0058] S9-2: The steel pipe is added to a 75% ethanol solution and sonicated for 20 minutes. It is then dried in a vacuum drying oven at 60°C for 12 hours. The surface of the steel pipe is then subjected to high-energy shot peening to make its surface nano-sized, thus obtaining the pretreated steel pipe.

[0059] S9-3: Spin-coating the coating onto the inside of the pretreated steel pipe, and drying it to obtain the coating with a thickness of 50 μm. Example 2

[0060] An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, wherein the formulation 2 of the high-pressure hydrogen transport and storage coating is as follows (by weight): 60 parts waterborne polyurethane emulsion, 30 parts modified cellulose nanocrystals, 5 parts composite filler, 5 parts polypropylene glycol, 2 parts silane coupling agent KH560, and 121 parts alcohol ester.

[0061] The preparation method of the composite filler is as follows:

[0062] S1-1: Add 10 parts by weight of nano-sized sodium-based montmorillonite to 280 parts by weight of deionized water and stir at 40°C for 1.5 h to obtain suspension A;

[0063] S1-2: Add 5 parts by weight of methyldodecylbis(hydroxyethyl)ammonium chloride to 90 parts by weight of deionized water, sonicate for 30 min, then add 1 part by weight of 6M hydrochloric acid solution, and continue sonicating for 30 min to obtain solution B.

[0064] S1-3: Add solution B dropwise to suspension A at a rate of 1 mL / min, stir at 80 °C for 1.5 h, filter and wash with 70% ethanol solution, dry at 100 °C for 12 h to obtain powder C;

[0065] S1-4: Mix 10 parts by weight of zirconium isopropoxide and 70 parts by weight of 50% ethanol solution, add powder C, reflux at 60°C for 1 hour, wash with deionized water and anhydrous ethanol, calcine in a muffle furnace for 1 hour at 400°C, and then ball mill in a ball mill for 1.5 hours at a speed of 400 r / min to obtain the composite filler.

[0066] The preparation method of modified cellulose nanocrystals is as follows:

[0067] S2-1: Add 20 parts by weight of cellulose nanocrystals to 60 parts by weight of deionized water and disperse at a stirring speed of 800 r / min for 30 min to obtain suspension D;

[0068] S2-2: Add 3 parts by weight of stearic acid to 20 parts by weight of anhydrous ethanol and stir at 80°C for 1 hour to obtain solution E;

[0069] S2-3: Mix suspension D and solution E, stir at 70°C for 1.5 h, wash with deionized water and anhydrous ethanol, freeze dry in a -30°C freeze dryer for 12 h to obtain the modified cellulose nanocrystals.

[0070] A method for preparing an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, the specific steps of which are as follows:

[0071] S9-1: Mix waterborne polyurethane emulsion, modified cellulose nanocrystals, composite filler, polypropylene glycol, silane coupling agent KH560 and alcohol ester 12 for 30 min according to formula 2 to obtain coating.

[0072] S9-2: The steel pipe is added to a 75% ethanol solution and sonicated for 20 minutes. It is then dried in a vacuum drying oven at 60°C for 12 hours. The surface of the steel pipe is then subjected to high-energy shot peening to make its surface nano-sized, thus obtaining the pretreated steel pipe.

[0073] S9-3: Spin-coating the coating onto the inside of the pretreated steel pipe, and drying it to obtain the coating with a thickness of 50 μm. Example 3

[0074] An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, wherein the high-pressure hydrogen transport and storage coating formulation 3 is as follows (by weight): 80 parts waterborne polyurethane emulsion, 40 parts modified cellulose nanocrystals, 15 parts composite filler, 7 parts polyethylene glycol, 3 parts silane coupling agent KH570, and 122 parts alcohol ester.

[0075] The preparation method of the composite filler is as follows:

[0076] S1-1: Add 20 parts by weight of nano-sized sodium-based montmorillonite to 300 parts by weight of deionized water and stir at 40°C for 1.5 h to obtain suspension A;

[0077] S1-2: Add 10 parts by weight of methyldodecylbishydroxyethylammonium chloride to 100 parts by weight of deionized water, sonicate for 30 min, then add 2 parts by weight of 6M hydrochloric acid solution, and continue sonicating for 30 min to obtain solution B.

[0078] S1-3: Add solution B dropwise to suspension A at a rate of 1 mL / min, stir at 80 °C for 1.5 h, filter and wash with 70% ethanol solution, dry at 100 °C for 12 h to obtain powder C;

[0079] S1-4: Mix 20 parts by weight of zirconium isopropoxide and 90 parts by weight of 50% ethanol solution, add powder C, reflux at 60°C for 1 hour, wash with deionized water and anhydrous ethanol, calcine in a muffle furnace for 1 hour at 600°C, and then ball mill in a ball mill for 1.5 hours at a speed of 500 r / min to obtain the composite filler.

[0080] The preparation method of modified cellulose nanocrystals is as follows:

[0081] S2-1: Add 40 parts by weight of cellulose nanocrystals to 80 parts by weight of deionized water and disperse at a stirring speed of 1000 r / min for 30 min to obtain suspension D;

[0082] S2-2: Add 5 parts by weight of stearic acid to 30 parts by weight of anhydrous ethanol and stir at 90°C for 1 hour to obtain solution E;

[0083] S2-3: Mix suspension D and solution E, stir at 80°C for 1.5 h, wash with deionized water and anhydrous ethanol, freeze dry in a -30°C freeze dryer for 12 h to obtain the modified cellulose nanocrystals.

[0084] A method for preparing an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, the specific steps of which are as follows:

[0085] S9-1: Mix waterborne polyurethane emulsion, modified cellulose nanocrystals, composite filler, polyethylene glycol, silane coupling agent KH570 and alcohol ester 12 for 30 min according to formula 3 to obtain coating.

[0086] S9-2: The steel pipe is added to a 75% ethanol solution and sonicated for 20 minutes. It is then dried in a vacuum drying oven at 60°C for 12 hours. The surface of the steel pipe is then subjected to high-energy shot peening to make its surface nano-sized, thus obtaining the pretreated steel pipe.

[0087] S9-3: Spin-coating the coating onto the inside of the pretreated steel pipe, and drying it to obtain the coating with a thickness of 50 μm.

[0088] Comparative Example 1

[0089] No modification was made to the cellulose nanocrystals; the remaining steps were the same as in Example 1.

[0090] Comparative Example 2

[0091] Zirconium isopropoxide was not added during the preparation of the composite filler, and the remaining steps were the same as in Example 1.

[0092] Comparative Example 3

[0093] Without adding composite fillers, the remaining steps are the same as in Example 1.

[0094] Comparative Example 4

[0095] Without adding modified cellulose nanocrystals, the remaining steps are the same as in Example 1.

[0096] The hydrogen permeability coefficients of the coatings prepared in the examples and comparative examples were determined according to GB / T42610-2023 standard. The test pressure was 1.15 times the nominal working pressure of the gas cylinder (70MPa), and the test temperature was 15℃.

[0097] The adhesion of the coatings prepared in the examples and comparative examples was determined according to GB / T23257 standard. The test temperature was 75℃ and the test time was 48h.

[0098] The experimental data are summarized in the table below.

[0099]

[0100] As can be seen from the examples and comparative data, the coating obtained by combining cellulose nanocrystals modified with stearic acid, and then using fillers obtained by combining montmorillonite and zirconium oxide with waterborne polyurethane emulsion and other additives has good substrate adhesion and hydrogen barrier properties.

[0101] The chemical resistance of the coating prepared in Example 1 was tested, and the experimental data are summarized in the table below.

[0102]

[0103] Note: Performance of the coating after 18 months of exposure to the container;

[0104] G = Excellent, L = Good.

[0105] As shown in the table above, the coating obtained by modifying cellulose nanocrystals with stearic acid, and then using montmorillonite and zirconium oxide composite filler, combined with water-based polyurethane emulsion and other additives, exhibits excellent chemical resistance and shows excellent stability against most chemical reagents.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating, characterized in that, The formulation of the high-pressure hydrogen transport and storage coating is as follows (by weight): 60-80 parts aqueous polyurethane emulsion, 30-40 parts modified cellulose nanocrystals, 5-15 parts composite filler, 5-7 parts dispersant, 2-3 parts crosslinking agent, and 1-2 parts film-forming aid. The preparation method of the composite filler is as follows: S1-1: Add 10-20 parts by weight of nano-sized sodium-based montmorillonite to 280-300 parts by weight of deionized water and stir at 40°C for 1.5 h to obtain suspension A; S1-2: Add 5-10 parts by weight of methyldodecylbis(hydroxyethyl)ammonium chloride to 90-100 parts by weight of deionized water, sonicate for 30 minutes, then add 1-2 parts by weight of hydrochloric acid solution, and continue sonicating for 30 minutes to obtain solution B. S1-3: Add solution B dropwise to suspension A, stir at 80℃ for 1.5h, filter and wash with 70% ethanol solution, dry at 100℃ for 12h to obtain powder C; S1-4: Mix 10-20 parts by weight of zirconium isopropoxide and 70-90 parts by weight of 50% ethanol solution, add powder C, reflux at 60°C for 1 hour, wash with deionized water and anhydrous ethanol, calcine in a muffle furnace for 1 hour at 400-600°C, and then ball mill in a ball mill for 1.5 hours at a speed of 400-500 r / min to obtain the composite filler.

2. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The method for preparing the modified cellulose nanocrystals is as follows: S2-1: Add 20-40 parts by weight of cellulose nanocrystals to 60-80 parts by weight of deionized water and disperse at a stirring speed of 800-1000 r / min for 30 min to obtain suspension D; S2-2: Add 3-5 parts by weight of stearic acid to 20-30 parts by weight of anhydrous ethanol, stir at 80-90℃ for 1 hour to obtain solution E; S2-3: Mix suspension D and solution E, stir at 70~80℃ for 1.5h, wash with deionized water and anhydrous ethanol, and freeze dry in a freeze dryer to obtain the modified cellulose nanocrystals.

3. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The dispersant is one of polyethylene glycol and polypropylene glycol.

4. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The crosslinking agent is one or more of the silane coupling agents KH550, KH560 and KH570.

5. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The concentration of the hydrochloric acid solution in S1-2 is 6M.

6. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The dropping rate of solution B in S1-3 is 1 mL / min.

7. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The freeze-drying temperature of the freeze dryer in S2-3 is -30℃, and the freeze-drying time is 12h.

8. The environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating according to claim 1, characterized in that, The film-forming aid is alcohol ester 12.

9. A method for preparing an environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating as described in claims 1-8, characterized in that, The specific steps of the preparation method are as follows: S9-1: Mix the waterborne polyurethane emulsion, modified cellulose nanocrystals, composite filler, dispersant, crosslinking agent and film-forming aid according to the formula for 30 minutes to obtain the coating; S9-2: The steel pipe is added to a 75% ethanol solution and sonicated for 20 minutes. It is then dried in a vacuum drying oven at 60°C for 12 hours. The surface of the steel pipe is then subjected to high-energy shot peening to make its surface nano-sized, thus obtaining the pretreated steel pipe. S9-3: Spin-coating the coating onto the inside of the pretreated steel pipe and drying it to obtain the coating.

10. An application of the environmentally friendly, chemically resistant, high-pressure hydrogen transport and storage coating as described in claims 1-9, characterized in that, The coating can be applied to hydrogen pipelines and hydrogen storage cylinders.

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